Dielectric ceramic composition and multilayer ceramic capacitor comprising the same

ABSTRACT

A dielectric ceramic composition and a multilayer ceramic capacitor including the same are provided. The dielectric ceramic composition includes a BaTiO3-based base material main ingredient and an accessory ingredient, where the accessory ingredient includes dysprosium (Dy) and niobium (Nb) as first accessory ingredients. A total content of the Dy and Nb is greater than 0.2 mol and less than or equal to 1.5 mol based on 100 mol of titanium (Ti) of the base material main ingredient.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.16/803,779, filed on Feb. 27, 2020, now U.S. Pat. No. 11,222,749 issuedJan. 11, 2022, which claims benefit of priority to Korean PatentApplication No. 10-2019-0070784 filed on Jun. 14, 2019, the disclosuresof which are incorporated herein by reference in their entireties.

BACKGROUND 1. Technical Field

The present disclosure relates to a dielectric ceramic compositionhaving improved reliability and a multilayer ceramic capacitor includingthe same.

2. Description of Related Art

Generally, electronic components using a ceramic material such as acapacitor, an inductor, a piezoelectric element, a varistor, athermistor, or the like, include a ceramic body formed of a ceramicmaterial, internal electrodes formed in the body and external electrodesmounted on a surface of the ceramic body to be connected to the internalelectrodes.

As there is a recent trend for electronic products to be miniaturizedand multifunctionalized along with chip components, there is a need formultilayer ceramic capacitors which are smaller in size but which havegreater capacity.

A method for both miniaturizing a multilayer ceramic capacitor andincreasing the capacity thereof simultaneously is to reduce thicknessesof the internal dielectric layers and electrode layers to laminate alarger number of the layers. Currently, the thickness of the internaldielectric layer is about 0.6 μm, and there have been efforts to developthinner dielectric layers.

Under such circumstances, ensuring reliability of dielectric layers isemerging as a major issue of dielectric materials. In addition,difficulties in managing quality and yield have become an issue due toincreased degradation of insulation resistance of dielectric materials.

To resolve such problems, there is a need to develop a new method forensuring high reliability with respect not only to a structure of amultilayer ceramic capacitor, but also a composition of a dielectric.

When a dielectric composition capable of improving the currentreliability is secured, a thinner multilayer ceramic capacitor can bemanufactured.

SUMMARY

As aspect of the present disclosure relates is to provide a dielectricceramic composition having improved reliability and a multilayer ceramiccapacitor including the same.

According to an aspect of the present disclosure, a dielectric ceramiccomposition includes a barium titanate (BaTiO₃)-based base material mainingredient and an accessory ingredient, where the accessory ingredientincludes dysprosium (Dy) and niobium (Nb) as first accessoryingredients. A total content of Dy and Nb is greater than 0.2 mol andless than or equal to 1.5 mol based on 100 mol of titanium (Ti) of thebase material main ingredient.

According to another aspect of the present disclosure, a multilayerceramic capacitor includes a ceramic body including dielectric layersand first and second internal electrodes disposed to face each otherwith respective dielectric layers interposed therebetween, and first andsecond external electrodes disposed on external surfaces of the ceramicbody where the first external electrode is electrically connected to thefirst internal electrode and the second external electrode iselectrically connected to the second internal electrode. The dielectriclayers include dielectric grains including a dielectric ceramiccomposition, and the dielectric ceramic composition includes aBaTiO₃-based base material main ingredient and an accessory ingredient,where the accessory ingredient includes Dy and Nb as first accessoryingredients. A total content of Dy and Nb is greater than 0.2 mol andless than or equal to 1.5 mol based on 100 mol of Ti of the basematerial main ingredient.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic perspective view of a multilayer ceramic capacitoraccording to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional view taken along line I-I′ in FIG. 1 ;

FIGS. 3A to 3C are graphs of high accelerated life test (HALT) testingresults according to the Embodiment Examples of the present disclosureand Comparative Examples; and

FIGS. 4A to 4E are graphs of HALT testing results according to theEmbodiment Examples of the present disclosure and Comparative Examples.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described asfollows with reference to the attached drawings. The present disclosuremay, however, be embodied in many different forms and should not beconstrued as being limited to the embodiments set forth herein. Rather,these embodiments are provided so that the present disclosure will bethorough and complete, and will fully convey the scope of the presentdisclosure to those skilled in the art. In the drawings, the shapes anddimensions of elements may be exaggerated for clarity, and the samereference numerals will be used throughout to designate the same or likeelements.

FIG. 1 is a schematic perspective view of a multilayer ceramic capacitoraccording to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view taken along line I-I′ in FIG. 1 .

Referring to FIGS. 1 and 2 , a multilayer ceramic capacitor 100according to an embodiment includes a ceramic body 110 includingdielectric layers 111 and first and second internal electrodes 121 and122 disposed to face each other with respective dielectric layersinterposed therebetween and first and second external electrodes 131 and132 disposed on external surfaces of the ceramic body 110. The firstexternal electrode 131 is electrically connected to the first internalelectrode 121 and the second external electrode 132 is electricallyconnected to the second internal electrode 122.

In regard to the multilayer ceramic capacitor 100 according to anembodiment, the “length direction,” “width direction,” and “thicknessdirection” of FIG. 1 are defined as an “L” direction, a “W” direction,and a “T” direction, respectively. The “thickness direction” may be usedin the same sense as a direction in which the dielectric layers arestacked up, for example, a “lamination direction.”

Although not particularly limited, a configuration of the ceramic body110 may be a rectangular cuboid shape as illustrated in the drawing.

A plurality of the first and second internal electrodes 121 and 122formed inside the ceramic body 110 have one end exposed to one surfaceof the ceramic body 110 or the other surface thereof disposed oppositethereto.

The internal electrodes may include a first internal electrode 121 and asecond internal electrode 122 having different polarities in pairs.

One end of the first internal electrode 121 may be exposed to onesurface of the ceramic body, and one end of the second internalelectrode 122 may be exposed to the other surface of the ceramic bodydisposed opposite thereto.

The first and second external electrodes 131 and 132 are formed on theone surface of the ceramic body 110 and the other surface disposedopposite thereto, respectively, to be electrically connected to theinternal electrodes.

Materials of the first and second internal electrodes 121 and 122 arenot particularly limited, and may be a conductive paste containing atleast one of the elements selected from the group consisting of, forexample, silver (Ag), lead (Pb), platinum (Pt), nickel (Ni) and copper(Cu).

The first and second external electrodes 131 and 132 may be electricallyconnected to the first and second internal electrodes 121 and 122,respectively, to generate capacitance. The second external electrode 132may be connected to an electric potential different from that connectedto the first external electrode 131.

A conductive material contained in the first and second externalelectrodes 131 and 132 is not particularly limited, but may include atleast one element selected from the group consisting of nickel (Ni),copper (Cu), and alloys thereof.

Thicknesses of the first and second external electrodes 131 and 132 maybe appropriately determined according to uses thereof, or the like, andare not particularly limited, but may be, for example, 10 μm to 50 μm.

According to an embodiment, a material forming the dielectric layers 111is not particularly limited as long as sufficient capacitance may beobtained therewith, and is not particularly limited, and may be, forexample, barium titanate (BaTiO₃) powder.

The material forming the dielectric layers 111 may include variousadditives, organic solvents, plasticizers, binders, dispersants, and thelike, added to BaTiO₃ powder, or the like.

The dielectric layers 111, in a sintered state, may be integrated in asingle body such that boundaries between neighboring dielectric layers111 may not be readily apparent.

The first and second internal electrodes 121 and 122 may be formed onthe dielectric layers 111, and the internal electrodes 121 and 122 maybe formed inside the ceramic body 110 by sintering while having onedielectric layer therebetween.

A thickness of the dielectric layer 111 may be optionally changedaccording to capacity design of the capacitor. A thickness of thedielectric layer in an embodiment after sintering may be 0.4 μm or lessper layer.

Further, thicknesses of the first and second internal electrodes 121 and122 after the sintering may be 0.4 μm or less per layer.

According to an embodiment, the dielectric layers 111 include dielectricgrains including a dielectric ceramic composition. The dielectricceramic composition includes a BaTiO₃-based base material mainingredient (base material main ingredient) and an accessory ingredient,where the accessory ingredient includes dysprosium (Dy) and niobium (Nb)as first accessory ingredients. A total content of Dy and Nb in thedielectric ceramic composition may be greater than 0.2 mol and less thanor equal to 1.5 mol based on 100 mol of titanium (Ti) of the basematerial main ingredient.

Relatively, many rare-earth elements are generally added to thedielectric composition used for the dielectric layer 111 to securereliability of the dielectric inside the multilayer ceramic capacitor.

Dysprosium (Dy) among such rare-earth elements decreases an oxygenvacancy concentration while substituting a barium (Ba)-site when Dy isadded to BaTiO₃ of the base-material main ingredient. Thus, Dy is knownto have an effect of improving reliability.

On the other hand, when a rare-earth element having an ion radius islarger than that of Dy, for example, lanthanum (La), samarium (Sm), orthe like, is added to the dielectric ceramic composition, an oxygenvacancy concentration is more effectively decreased as the Ba-site maybe more effectively substituted. In this case, however, the rare-earthelement may not be able to actually apply due to insulation resistancerapidly reduced by excessive semiconductorization.

Accordingly, it is considered that novel rare-earth elements may beadded to the dielectric ceramic composition to secure insulationresistance while minimizing oxygen vacancy concentration to improvereliability.

In an embodiment, an optimal content ratio of the rare-earth elementsmay be determined to secure excellent reliability by including Nb inaddition to Dy in the dielectric ceramic composition, which show stabledielectric characteristics.

According to an embodiment, the dielectric ceramic composition includesa BaTiO₃-based base material main ingredient (base material mainingredient) and an accessory ingredient. The accessory ingredientincludes Dy and Nb as the first accessory ingredients. In this case, atotal content of the Dy and Nb is greater than 0.2 mol and less than orequal to 1.5 mol based on 100 mol of Ti of the base material mainingredient.

The reliability such as insulation resistance, or the like, may beimproved by adjusting the total content of Dy and Nb in the dielectricceramic composition to be greater than 0.2 mol and less than or equal to1.5 mol based on 100 mol of Ti of the base material main ingredient.

When the total content of the Dy and Nb in the dielectric ceramiccomposition is 0.2 mol or less based on 100 mol of Ti of the basematerial main ingredient, the total content of the rare-earth elementsDy and Nb is too little and thus, a reliability improvement effect isnot significant.

In terms of reliability improvement, it is more advantageous as thetotal content of the Dy and Nb in the dielectric ceramic compositionincreases; however, the Dy and Nb are semiconductorized at a certainamount or more, thereby deteriorating the characteristics of aninsulator as well as sinterability. Accordingly, the total content of Dyand Nb in the dielectric ceramic composition may be 1.5 mol or lessbased on 100 mol of Ti of the base material main ingredient.

In other words, when the total content of the Dy and Nb in thedielectric ceramic composition exceeds 1.5 mol based on 100 mol of Ti ofthe base material main ingredient, lack of sinterability resulting fromthe excessive content of the rare-earth elements may cause problems ofan insufficient capacity and reliability deterioration.

In detail, according to an embodiment, the Nb content in the dielectricceramic composition may satisfy 0.05 mol≤Nb≤0.20 mol based on 100 mol ofTi of the base material main ingredient.

When the Nb content in the dielectric ceramic composition satisfies 0.05mol≤Nb≤0.20 mol based on 100 mol of Ti of the base material mainingredient, the reliability improvement effect such as insulationresistance improvement may be excellent.

When the Nb content in the dielectric ceramic composition is less than0.05 mol based on 100 mol of Ti of the base material main ingredient,the Nb content is too little and thus the reliability improvement effectmay not be significant.

On the other hand, when the Nb content in the dielectric ceramiccomposition exceeds 0.20 mol based on 100 mol of Ti of the base materialmain ingredient, insulation resistance may be reduced due tosemiconductorization.

According to an embodiment, with respect to the dielectric ceramiccomposition included in dielectric layers in the ceramic body, highdielectric characteristics may be obtained and the reliability such asinsulation resistance may be improved by including rare-earth elementsDy and Nb as accessory ingredients while controlling the contentsthereof.

According to an embodiment, Nb may be disposed at a boundary of thedielectric grain.

Disposed at the boundary of the dielectric grain, Nb may inhibit areduction in the insulation resistance of the multilayer ceramiccapacitor, thereby improving reliability.

The multilayer ceramic capacitor 100 according to an embodiment is aminiaturized product with high capacity, and includes a dielectric layer111 having a thickness of 0.4 μm or less and the first and secondelectrodes 121 and 122 having a thickness of 0.4 μm or less, but thethickness is not particularly limited thereto. The thickness of thedielectric layer 111 is more than 0.0 μm.

Additionally, a size of the multilayer ceramic capacitor 100 may be1005(length×width, 1.0 mm×0.5 mm) or less.

For example, as the multilayer ceramic capacitor 100 according to anembodiment is a miniaturized product with high capacity, the thicknessesof the dielectric layers 111 and the first and second internalelectrodes 121 and 122 are thinner than those of related art products.With respect to such a product to which thin film dielectric layers andinternal electrodes are applied, research for improving reliability suchas insulation resistance is a significantly important issue.

In detail, as related art multilayer ceramic capacitors havecomparatively thicker dielectric layers and internal electrodes comparedto the multilayer ceramic capacitor according to an embodiment,reliability is not a big issue even though a composition of thedielectric ceramic composition is the same as that of the related art.

However, in regard to a product of a multilayer ceramic capacitor towhich thin film dielectric layers and internal electrodes are applied asin an embodiment of the present disclosure, reliability of themultilayer ceramic capacitor is important, and it is necessary to adjustthe composition of the dielectric ceramic composition.

For example, in an embodiment, even when the dielectric layer 111 is athin film having a thickness of 0.4 μm or less, reliability such asinsulation resistance may be improved by including Dy and Nb as thefirst accessory ingredients and adjusting the total content thereof tobe greater than 0.2 mol and be equal to or less than 1.5 mol based on100 mol of Ti of the base material main ingredient, and in more detail,by adjusting the Nb content to satisfy 0.05 mol≤Nb≤0.20 mol based on 100mol of Ti of the base material main ingredient.

In this case, however, the thin film does not mean that the thicknessesof the dielectric layers 111 and internal electrodes 121 and 122 are 0.4μm or less, and may be understood in a sense that the dielectric layersand internal electrodes are thinner than those of related art products.

Hereinafter, each ingredient of the dielectric ceramic compositionaccording to an embodiment will be described in more details.

(a) Base Material Main Ingredient

The dielectric ceramic composition according to an embodiment of thepresent disclosure may include a base material main ingredientrepresented by BaTiO₃.

According to an embodiment, the base material main ingredient includesat least one compound selected from the group consisting of BaTiO₃,(Ba_(1-x)Ca_(x)) (Ti_(1-y)Ca_(y))O₃ (where 0≤x≤0.3, 0≤y≤0.1),(Ba_(1-x)Ca_(x)) (Ti_(1-y)Zr_(y))O₃ (where 0≤x≤0.3, 0≤y≤0.5), and Ba(Ti_(1-y)Zr_(y))O₃ (where 0<y≤0.5), but is not necessarily limitedthereto.

The dielectric ceramic composition according to an embodiment may haveroom-temperature permittivity of 2000 or above.

The base material main ingredient is not particularly limited, but anaverage diameter of the main ingredient powder may be 40 nm or above and200 nm or less.

b) First Accessory Ingredient

According to an embodiment of the present disclosure, the dielectricceramic composition includes Dy and Nb as elements of the firstaccessory ingredients.

The first accessory ingredient serves to inhibit reliabilitydeterioration of the multilayer ceramic capacitor to which thedielectric ceramic composition is applied in an embodiment.

According to an embodiment, reliability such as insulation resistancecan be improved even when the thickness of the dielectric layer 111 is0.4 μm or less, by including Dy and Nb as the first accessoryingredients, adjusting the total content of Dy and Nb in the dielectricceramic composition to be greater than 0.2 mol and 1.5 mol or less basedon 100 mol of Ti of the base material main ingredient, and in moredetail, adjusting the Nb content in the dielectric ceramic compositionto satisfy 0.05 mol Nb≤0.20 mol based on 100 mol of Ti of the basematerial main ingredient. The Nb content of the present disclosure maybe the Nb content included in the dielectric layer 111. The totalcontent of Dy and Nb of the preset disclosure may be the total contentof Dy and Nb included in the dielectric layer 111. The Nb content of thepresent disclosure may be an atom percent (at. %) of Nb in thedielectric composition based on 100 mol % of Ti of the base materialmain ingredient in the dielectric composition.

c) Second Accessory Ingredient

According to an embodiment of the present disclosure, the dielectricceramic composition may include one or more oxides including at leastone element selected from the group consisting of manganese (Mn),vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt(Co), copper(Cu) and zinc (Zn) and/or one or more carbonates including at least oneelement selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cuand Zn as the second accessory ingredient.

As the second accessory ingredient, a total amount of the oxidesincluding at least one element selected from the group consisting of Mn,V, Cr, Fe, Ni, Co, Cu and Zn and the carbonates including at least oneelement selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cuand Zn may be included in an amount of 0.1 mol to 2.0 mol based on 100mol of Ti of the base material main ingredient.

The second accessory ingredient serves to lower a firing temperature andenhance high temperature-withstand voltage characteristics of themultilayer ceramic capacitor to which the dielectric ceramic compositionis applied.

The contents of the second accessory ingredient and third and fourthaccessory ingredients described in the present disclosure may be theamounts contained in the dielectric ceramic composition based on 100 molof the base material powder, and may be defined as moles of metal ionsin which respective accessory ingredients are contained. The contents ofthe second accessory ingredient and third and fourth accessoryingredients of the present disclosure may be the contents included inthe dielectric layer 111.

When the content of the second accessory ingredient is less than 0.1mol, the firing temperature increases and the high temperature-withstandvoltage characteristics somewhat decreases.

When the content of the second accessory ingredient is greater than 2.0mol, the high temperature-withstand voltage and room-temperaturespecific resistance may deteriorate.

In detail, the dielectric ceramic composition according to an embodimentmay include 0.1 mol to 2.0 mol, inclusive, of the second accessoryingredient based on 100 mol of the base material main ingredient. Thiswill enable firing at a low temperature and provide the hightemperature-withstand voltage characteristics.

Third Accessory Ingredient

According to an embodiment of the present disclosure, the dielectricceramic composition may include a third accessory ingredient, which isan oxide and/or carbonate including a fixed-valence acceptor element ofmagnesium (Mg).

The fixed-valence acceptor element Mg may be included as the thirdaccessory ingredient in an amount of 0.2 mol to 0.7 mol, inclusive,based on based on 100 mol of Ti of the base material main ingredient.

The third accessory ingredient, as a fixed-valence acceptor element orcompounds including the same, serves as an acceptor to decrease anelectron concentration. The reliability improvement effect due to n-typemay be significantly increased by adding 0.2 mol to 0.7 mol, inclusive,of the fixed-valence acceptor element Mg, which is the third accessoryingredient, based on 100 mol of Ti of the base material main ingredient.

When the content of the third accessory ingredient is greater than 0.7mol based on 100 mol of Ti of the base material main ingredient, thepermittivity may decrease and a dielectric breakdown voltage (BDV) maydecrease, which may be problematic.

Fourth Accessory Ingredient

According to an embodiment of the present disclosure, the dielectricceramic composition may include, as the fourth accessory ingredient, oneor more oxides including at least one element of silicon (Si) oraluminum (Al), or a glass compound including Si.

The dielectric ceramic composition may further include 0.5 mol or lessand more than 0.0 mol of the fourth accessory ingredient, which includesone or more oxides including at least one element of Si or Al, or aglass compound including Si, based on 100 mol of the base material mainingredient.

The fourth accessory ingredient content may be the content of theelements of Si and Al contained in the dielectric ceramic composition asthe fourth accessory ingredient regardless of an additional form such asglass, oxides or carbonates.

The fourth accessory ingredient serves to lower a firing temperature andimprove high-temperature withstand voltage characteristics of themultilayer ceramic capacitor to which the dielectric ceramic compositionis applied.

When the fourth accessory ingredient content exceeds 0.5 mol based on100 mol of the base material main ingredient, there may be problems suchas decreased sinterability and density, secondary phase formation, orthe like, which may be problematic.

In detail, according to an embodiment, when the dielectric ceramiccomposition contains 0.5 mol or less of Al, Al serves as an acceptor anddecreases the electron concentration, thereby improving reliability.

Hereinafter, the present disclosure will be described in more detailwith respect to the embodiments of the present disclosure andcomparative examples. These embodiments and comparative examples areprovided to assist in a comprehensive understanding of the invention,and should not be construed as being limited to the embodiments setforth herein.

Embodiment Examples

A dielectric layer were formed by adding an additive such as Dy, Nb, Al,Mg, Mn, or the like, a binder and an organic solvent, such as ethanol,to dielectric powder particles containing BaTiO₃ as a base material mainingredient, and wet-mixing the same to prepare a dielectric slurryfollowed by spreading and drying the dielectric slurry on a carrier filmto prepare a ceramic green sheet.

All element additives having a particle size of 40% or less based onBaTiO₃ were monodispersed and added.

In the Embodiment Examples of the present disclosure, a multilayerceramic capacitor was manufactured such that the total content of Dy andNb in the dielectric slurry was greater than 0.2 mol and less than orequal to 1.5 mol based on 100 mol of Ti of the base material mainingredient; in detail, the Nb content satisfied 0.05 mol≤Nb≤0.20 molbased on 100 mol of Ti of the base material main ingredient.

The total content of Dy and Nb added to the dielectric slurry (i.e., thetotal content of Dy and Nb in the dielectric ceramic composition) inEmbodiment Example 1 was 1.5 mol based on 100 mol of Ti of the basematerial main ingredient.

The Nb contents added to the dielectric slurry (i.e., the total contentof Dy and Nb in the dielectric ceramic composition) in EmbodimentExamples 2 to 4 respectively were 0.05 mol, 0.1 mol and 0.20 mol,respectively, based on 100 mol of Ti of the base material mainingredient.

The ceramic green sheet was fabricated as a sheet having a thickness ofseveral micrometers by mixing the ceramic powder, a binder and a solventto prepare a slurry and using the slurry subjected to a doctor blademethod.

Then, a conductive paste for internal electrodes including 40 parts byweight to 50 parts by weight of nickel powder having an average particlesize of 0.1 μm to 0.2 μm was prepared.

The conductive paste for internal electrodes was screen-printed on theceramic green sheets to form internal electrodes. The green sheets onwhich internal electrode patterns were formed were then laminated toform a laminate followed by compressing and cutting the laminate.

Then, the cut laminate was heated to remove the binder, and fired in ahigh-temperature reducing atmosphere to form a ceramic body.

During the firing process, a heat treatment was performed by firing in areducing atmosphere (0.1% H₂/99.9% N₂, H₂O/H₂/N₂) at 1100° C. to 1200°C. for 2 hours followed by reoxidation in a nitrogen (N₂) atmosphere at1000° C. for 3 hours.

A copper (Cu) paste was used to perform a termination process andelectrode firing for the fired ceramic body, and external electrodeswere formed.

In addition, the dielectric layers 111 and the first and second internalelectrodes 121 and 122 inside the ceramic body 110 were manufactured soas to have a thickness of 0.4 μm or less after firing.

COMPARATIVE EXAMPLE 1

In Comparative Example 1, the total content of Dy and Nb in thedielectric ceramic composition was 1.8 mol, which exceeds 1.5 mol, basedon 100 mol of Ti of the base material main ingredient. The remainingmanufacturing process was the same as that previously described.

COMPARATIVE EXAMPLE 2

In Comparative Example 2, the total content of Dy and Nb in thedielectric ceramic composition was 2.1 mol, which is exceeds 1.5 mol,based on 100 mol of Ti of the base material main ingredient. Theremaining manufacturing process was the same as that previouslydescribed.

COMPARATIVE EXAMPLE 3

In Comparative Example 3, Nb was not added in a dielectric layer as therelated art multilayer ceramic capacitor. The remaining manufacturingprocess was the same as that previously described.

COMPARATIVE EXAMPLE 4

In Comparative Example 4, 0.25 mol of Nb was added to the dielectricslurry (i.e., the total content of Dy and Nb in the dielectric ceramiccomposition), based on 100 mol of Ti of the base material mainingredient. The remaining manufacturing process was the same aspreviously described.

HALT testing was performed for samples of prototype multilayer ceramiccapacitors (prototype MLCC) manufactured in Examples 1 to 4 andComparative Examples 1 to 4 as described above.

FIGS. 3A to 3C are graphs of HALT testing results according to theEmbodiment Examples of the present disclosure and Comparative Examples.

FIG. 3A represents Embodiment Example 1 of the multilayer ceramiccapacitor samples, in which the total content of Dy and Nb was 1.5 molbased on 100 mol of Ti of the base material main ingredient. The HALTtesting shows the excellent reliability with no defect.

In the case of Embodiment Example 1, a normal capacity is 101% and BDVwas 63V, indicating excellent reliability in terms of capacity and BDV.

FIG. 3B represents Comparative Example 1, in which the total content ofDy and Nb was 1.8 mol, which exceeds 1.5 mol, based on 100 mol of Ti ofthe base material main ingredient, and FIG. 3C represents ComparativeExample 2, in which the total content of Dy and Nb was 2.1 mol, whichexceeds 1.5 mol, based on 100 mol of Ti of the base material mainingredient.

In both cases of Comparative Examples 1 and 2, several defects wereobserved in the HALT testing, indicating decreased reliability.

Further, normal capacity was 90% and BDV was 58V in Comparative Example1, and normal capacity was 82% and BDV was 47V in Comparative Example 2,indicating substandard reliability.

FIGS. 4A to 4E are graphs of HALT testing results according to theEmbodiment Examples of the present disclosure and Comparative Examples.

FIG. 4A represents Comparative Example 3, in which Nb was not added asin the related art. Several defects were detected in the HALT testing,indicating decreased reliability.

FIGS. 4B to 4D represent Embodiment Examples 2 to 4, in which 0.05 mol,0.1 mol and 0.20 mol of Nb were added based on 100 mol of Ti of the basematerial main ingredient, respectively. The HALT testing showed no or aminimum number of defects, indicating excellent reliability.

FIG. 4E represents Comparative Example 4, in which the Nb content was0.25 mol based on 100 mol of Ti of the base material main ingredient.Several defects were detected in the HALT testing, indicating decreasedreliability.

According to an embodiment, a dielectric ceramic composition included ina dielectric layer in a ceramic body may have improved reliability suchas improved insulation resistance by including as an accessoryingredient a novel rare-earth element Nb while controlling the contentthereof.

While example embodiments have been shown and described above, it willbe apparent to those skilled in the art that modifications andvariations could be made without departing from the scope of the presentdisclosure as defined by the appended claims.

What is claimed is:
 1. A multilayer ceramic capacitor, comprising: aceramic body comprising dielectric layers and first and second internalelectrodes disposed to face each other with respective dielectric layersinterposed therebetween; and a first external electrode and a secondexternal electrode disposed on external surfaces of the ceramic body,the first external electrode being connected to the first internalelectrode and the second external electrode being connected to thesecond internal electrode, wherein the dielectric layers comprisedielectric grains comprising a dielectric ceramic composition, thedielectric ceramic composition comprises a barium titanate(BaTiO3)-based base material main ingredient and an accessoryingredient, the accessory ingredient comprising dysprosium (Dy) andniobium (Nb) as first accessory ingredients, wherein a total content ofthe Dy and Nb is greater than 0.2 mol and less than or equal to 1.5 molbased on 100 mol of titanium (Ti) of the barium titanate-based basematerial main ingredient, and wherein a thickness of at least one of thedielectric layers is 0.4 μm or less.
 2. The multilayer ceramic capacitorof claim 1, wherein a content of the Nb satisfies 0.05 mol≤Nb≤0.20 molbased on 100 mol of Ti of the barium titanate base material mainingredient.
 3. The multilayer ceramic capacitor of claim 1, wherein thedielectric ceramic composition comprises 0.1 mol to 2.0 mol, inclusive,of a second accessory ingredient based on 100 mol of the barium titanatebase material main ingredient, wherein the second accessory ingredientcomprises one or more oxides comprising at least one element selectedfrom the group consisting of manganese (Mn), vanadium (V), chromium(Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu) and zinc (Zn)and/or one or more carbonates comprising at least one element selectedfrom the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn.
 4. Themultilayer ceramic capacitor of claim 1, wherein the dielectric ceramiccomposition comprises 0.2 mol to 0.7 mol, inclusive, of a thirdaccessory ingredient based on 100 mol of Ti of the barium titanate basematerial main ingredient, wherein the third accessory ingredient is anoxide or carbonate comprising a fixed-valence acceptor element ofmagnesium (Mg).
 5. The multilayer ceramic capacitor of claim 1, whereinthe dielectric ceramic composition comprises 0.001 mol to 0.5 mol of afourth accessory ingredient based on 100 mol of the barium titanate basematerial main ingredient, wherein the fourth accessory ingredientcomprises one or more oxides comprising at least one element of silicon(Si) or aluminum (Al), or a glass compound comprising Si.
 6. Themultilayer ceramic capacitor of claim 1, wherein a thickness of each ofthe first and second internal electrodes is 0.4 μm or less.
 7. Themultilayer ceramic capacitor of claim 1, wherein a size of themultilayer ceramic capacitor is 1005 (length×width, 1.0 mm×0.5 mm) orless.
 8. The multilayer ceramic capacitor of claim 1, wherein Nb isdisposed at a boundary of the dielectric grain.